Stratoflex, Inc. v. Aeroquip Corp.
United States Court of Appeals for the Federal Circuit
713 F.2d 1530 (1983)
Competitors Aeroquip Corporation (defendant) and Stratoflex, Inc. (plaintiff) both made conductive PTFE tubing, which historically leaked because gaps formed between the tubing and its conductive filler; Aeroquip's engineers traced the leakage to electrical erosion and developed a composite tube combining a PTFE layer with a second layer of PTFE mixed with conductive carbon-black filler, patenting the design (the '087 patent). When Stratoflex began making a similar composite tube with evenly dispersed carbon-black filler, Aeroquip accused it of infringement; Stratoflex sought a declaratory judgment that the patent was invalid, and Aeroquip counterclaimed for infringement. The district court found several claims of the '087 patent obvious in light of prior art and found no infringement of the one valid claim, and Aeroquip appealed both rulings.
Whether, for purposes of patent protection, the determination of whether an invention is obvious in light of prior art requires the consideration of several factors viewed as a whole.